Give the correct form of the verbs.
1. If we (not/ protect) __________ the environment, our life will be badly affected.
2. When we arrived at the station, the last train ( already/ leave) __________.
3. After he (do) __________ all his homework, he went out for a walk.
4. Chess (play) __________ for around two thousand years.
1. If we (not/ protect) _don't protect_________ the environment, our life will be badly affected.
2. When we arrived at the station, the last train ( already/ leave) __have already leaf________.
3. After he (do) __done________ all his homework, he went out for a walk.
4. Chess (play) _have played_________ for around two thousand years.